1. Field of the Invention
The present invention relates to an optical component that is used for an optical apparatus such as a digital camera or a copier and a method of making the optical component.
2. Description of the Related Art
There's an increasing demand for making thick optical components by using an injection molding method in recent years. However, as the thickness of an optical component increases, an increase in stress occurs due to the difference between contraction of a surface plastic layer, which first solidifies during a molding process, and contraction of an inner plastic portion, which solidifies afterwards. Therefore, problems in that a vacuum bubble (void) is generated in the optical component and a residual internal stress remains in the optical component occur. There is another problem in that a considerably long cycle time is required to mold a thick optical component, because a considerably longer cooling time is required to cool a thicker optical component.
To address such problems, an invention related to an optical component including a core lens whose front and back optical surfaces are integrated with each other through a covering plastic has been disclosed (Japanese Patent Laid-Open No. 8-187793). As optical apparatuses such as digital cameras and copiers are becoming more compact, smaller optical components for such apparatuses have been demanded. However, with the method described in Japanese Patent Laid-Open No. 8-187793, a cavity space that is larger than the outer shape of the core lens is formed in a mold and a covering plastic is introduced onto the front and back optical surfaces of the core lens. Therefore, the outer shape of the optical component becomes larger than that of the core lens, so that it is difficult to reduce the size of the optical component with this method.